Air-arming impact fuze



Nov. 7, 1967 J. A. MYERS 3,351,017

Y AIR-ARMING IMPACT FUZE Original Filed D60. 5. 1964 2 Sheet S-Sheet 1Ila FIG. IA. 24

FIG. 5.

INVENTOR. JACK A. MYERS FIG. 2.

ATTORNEY.

Nov. 7, 1967 J. A. MYERS AIRT'ARMING IMPACT FUZE Original Filed Dec. 5.1964 2 Sheets-Sheet 2 INVENTOR JACK A. M YE RS ATTOR N EY.

United States Patent f ABSTRACT OF THE DISCLOSURE An inertia member isrestrained in a safe a frustoconical washer which is deformed by adeceleration force, such as the opening of a parachute, permitting theinertia member to move to an arm position. Thereafter, the decelerationof impact permits the inertia member to move to fire position.

position by The invention described herein may be manufactured and usedby or for the Government of the United States of America forgovernmental purposes without the payment of any royalties thereon ortherefor.

The instant invention, a continuation of Ser. No. 415,840, filed Dec. 3,1964, now abandoned, relates generally to fuzes and more particularly toan improved airarming, impact-firing mechanical fuze of free-fallweapons.

Heretofore, various fuze mechanisms have been em ployed to fireair-delivered pyrotechnics on impact. However, known air-arming andimpact-firing mechanisms have not satisfied existing needs, as suchdevices generally require complex and expensive actuating mechanisms,are normally diflicult to assemble, are often unsafe to handle andstore, and are frequently found to be operatively unreliable.

Therefore, it is the purpose of the instant invention to overcome theaforementioned disadvantages, while improving over-all efiiciency. Thisis accomplished by providing a fuze for an air-delivered device, whichmay be coupled with existing hardware and ejected into an impingingairstream and subsequently armed as a malleable safety washer orbuttress is crushed as a consequence of imposed shock resulting from adeployment of an attached delivery parachute.

An object of the instant invention is to provide an airarming,impact-firing mechanical fuze having reliable means for maintaining apositive safe condition and a reliable firing operative function.

Another object is to provide a fuze which may be readily attached toexisting hardware and ejected from airborne aircraft, and subsequentlyarmed by an impinging airstream acting on a deployed parachute attachedthereto.

A further object is to provide a tamper-proof safety device having apositive retaining means for maintaining the fuze in a safe condition.

Still another object is to provide a simple, economic, andsafe-to-handle, air-delivered pyrotechnique device, which is capable ofdeploying a delivery parachute, with a high degree of reliability, andarming as a consequence of parachute deployment.

Yet another object is to provide a pop off fuze which may be attached toexisting pyrotechnic hardware for improving the burning characteristicsof the hardware when delivered from an airborne vehicle.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings wherein:

3,351,017 Patented Nov. 7, 1967 ice FIGS. 1A, 1B, and 1C comprisesuccessive views of an ejected device of the instant inventionundergoing parachute deployment and fuze-arming operations;

FIG. 2 is a partial cross sectional view, on an enlarged scale, takenalong a vertical central plane 2-2 of FIG. 1A, illustrating apredelivery fuze, parachute and parachute housing relationship;

FIG. 3 is a cross sectional view of the fuze, on an enlarged scale,taken generally along lines 3-3 of FIG. 2;

FIGS. 4 and 6 comprise alternate cross sectional views, taken generallyalong lines 44 of FIG. 3', illustrating an alternate positioning of thestab detonator and rotor bar, as provided for the device of the instantinvention in a safe, and subsequently, armed condition; and

FIG. 5 is a partial sectional view of the fuze of the instant inventionillustrating the fuze in an armed condition.

Turning now the the drawings, wherein like reference charactersdesignate like or corresponding parts throughout the several views,there is shown in FIG. 1A a grenade G including a pyrotechnic containerC having a predetermined type and quantity of pyrotechnic material Pdisposed therein. The grenade G is of a type which may be inserted intoand dispersed by ram air acting on a system such as that disclosed inapplicants copending application Ser. No. 415,828, filed Dec. 3, 1964,or from tubular racks provided for attacking aircraft, not shown. Uponbeing dispersed, a parachute 10 is deployed from a housing 11 and arms afuze F as the parachute opens and the grenade G descends at a rate whichmay be a non-lethal and non-destructive rate. Once the grenade Gimpacts, with a predetermined non-destructive force, the fuze isseparated and the pyrotechnic material of the grenade G is permitted toburn at both ends simultaneously to effect a desired result. Thepyrotechnic material P may comprise any one of a large number ofchemical materials which are to be ignited and burned for variouspurposes.

As it is often desirable to use the herein disclosed weapon as anon-lethal device, the parachute 10 may be of a size sufficient foraccommodating a descent rate of posed in a common plane, and

30 feet/second, which has been determined to be of a non-lethal rate.The housing 11 comprises a pair of connected clam shell-like members 11aand 11b utilized to encase the parachute 10 and fuze F, FIG. 2. Thehousing 11 may be fabricated as a unitary device of resilient syntheticplastic material. Thus in forming the housing 11, the members 11a and11b are preferably connected along one adjacent edge by a plastic film(not designated), which extends between the two members, as they arediswill, if deformed, tend to recover for forcing the members 11a and11b to assume an open condition wherein the members 11a and 11b areforced toward a common plane. Hence, when the grenade G is ejected intoan airstream the housing 11 pops open, as the members 11a and 11b tendto separate. As the members 11a and 11b separate, the airstream actsthereon to completely open the housing 11 and extract the parachute 10therefrom, whereupon the parachute 10 now becomes fully deployed forarming the fuze F, as will hereinafter be more fully explained, and thegrenade G lowered thereby to the ground or impact area.

As more clearly shown in FIG. 2, the parachute 10 is attached, throughits shroud lines 10a, to a shirt-like portion of a cap 12 and stored ina folded condition, about the fuze F, within the housing 11. Therefore,the grenade must necessarily be supported in descent by the cap 12. Thusforces of shock imposed through an opening of the parachute 10 will betransferred to the cap 12.

The cap 12, FIG. 3, is connected to an extended firing pin shaft 13passing outwardly through an opening 12' formed in the cap 12 andconcentrically arranged about the longitudinal axis of the fuze F. Theextended shaft 13 serves to add mass to a firing pin 14, connected to orformed at the shafts innermost end, and further serves to aid inaligning the fuze F within the housing 11. Any suitable means may beemployed for connecting the cap 12 and shaft 13. However, it ispreferred to provide the shaft 13 with a shoulder 13a, which abuts theinternal surface of the cap 12, and a lock ring 13b seated in anappropriate groove formed about the shaft 13in engagement with theexternal surface of the cap 12. Further, suitable O-ring seals 130 maybe provided to seal the shaft 13 relative to the cap 12.

The shaft is further provided with a shoulder 15, disposed inwardly fromthe cap 12, which serves as an abutment against which a relatively thinsafety washer or buttress 16 is seated for retaining the firing pin 14in an inwardly extended or a safe position within a cup-shaped fuzehousing 17 having an opening 17a formed therein for receiving the shaft13. The buttress 16 is formed to assume a generally frusto-conicalconfiguration from a malleable material, such as malleable aluminum, forexample, whereby a crushing of the buttress is required in order toretract or displace the firing pin 14 from its safe position.

In assembling the fuze, it is desirable to first pass the shaft 13through the washer or buttress 16 and then insert the shaft 13 throughthe opening 17a, which is provided at one end of the cup-shaped housing17 in coaxial alignment with the opening 12' of the cap 12. Thus thebuttress 16 is thus caused to assume a disposition wherein it engagesthe internal surface of the housing 17 while engaging the shoulder, andserves to maintain the shoulder in a displaced relationship relative tothe internal surfaces of the end portion of the housing 17. Hence, it isto be understood that shoulder 15 may not be displaced rearwardly exceptin instances where applied displacing forces are suificient for crushingor deforming the buttress 16.

Therefore, it is entirely feasible to predetermine and dictate theforces required for retracting or displacing the firing pin 14 from itssafe to its arm position. Thus the buttress 16 serves as a positivesafety device which is not subject to vibrations normally encountered inhandling and transporting the grenade G. Further, the fuze F is thusmade substantially tamper-proof, due to the fact that it is disposedentirely within the fuze housing 17, which, when assembled, is furtherprotected by the parachute 10 and housing 11. This characteristic isfound to be highly desirable in instances where the device is to beplaced in the hands of the inexperienced, or where the device is likelyto become accessible to unfriendly personnel.

Mounted to pivot about a pivot post 18, and normal to the longitudinalaxis of the fuze F, there is fixed a rotor bar 20, which may bedisplaced across the path of the firing pin 14 when the firing pin is inan armed position. The rotor bar 20 has formed therethrough an openinginto which a stab primer or detonator 22, of conventional design, FIG.6, is inserted and secured through a conventional staking process. Inorder to function as a means for initiating the grenade G, it isnecessary that the stab primer 22 be so disposed as to locate, When inarm position, in coaxial alignment with the firing pin 14, whereby thefiring pin may be caused to reciprocate for impinging on the surfacethereof. Consequently, for arming the fuze F, the rotor bar 20 must bepivotally displaced from a safe position, wherein the primer 22 is outof coaxial alignment with the firing pin 14, to its arm position thusaltering the successive positions assumed by the stab primer 22 as thedevice becomes armed.

It is to be particularly noted that when the device is in a safecondition, FIGS. 3 and 4, the firing pin 14 is fully extended inwardlyinto the fuze housing 17. Therefore, when a safe condition is imposed onthe fuze F, the firing pin 14 must necessarily extend into the path ofthe rotor bar 20 and thereby serve to block pivotal displacement of therotor bar 20 and thereby retain the stab primer 22 in a safe position,FIG. 4. Thus the firing pin 14 must be retracted from its safe positionto its armed position, FIG. 5, in order to accommodate a pivotaldisplacement of the rotor bar 20 to an armed position, as illustrated inFIG. 6, wherein the stab primer 22 is coaxially aligned with the firingpin 14.

The rotor bar 20, and the pivot pin 18, are supported on a transversebearing plate 23 which, in turn, is supported by a plurality ofsupporting bars 24 extending from a remotely disposed transversesupporting plate 24a, FIG. 3. Where desired, an additional transversebearing plate 23a may be provided adjacent the surface of the bar 20opposite the plate 23, and seated in a retainer ring 23b, for thusencasing the rotor bar 20 and providing opposed bearing surfaces uponwhich rotor bar bearings 20a may ride.

Mounted in coaxial alignment with the firing pin 14 is tubular conduit25 which extends through the bearing plate 23 and supporting plate 24a,or from the rotor bar 20 to an igniter wafer 26. The wafer 26 is formedof any suitable pyrotechnic composition which is capable of igniting theparticular pyrotechnic material P in response to its initiation,resulting from an explosion of the stab primer 22 and communicatedthereto through the conduit 25. The wafer 26 is seated over an opening27 formed in a container cover cap 28 and communicating with theselected pyrotechnic material P. The cover cap 28 is fixed to thecontainer C across a container opening 0.

Hence, it is readily apparent that when the device is in an armedcondition the firing pin 14 may be caused to impinge against the stabprimer or detonator 22 for causing an explosion thereof. By-products ofthe explosion are then directed through the conduit 25 for initiatingthe igniter wafer 26 which, in turn, fires through the opening 27 andinitiates the pyrotechnic material P.

In order to impart pivotal displacement to the rotor bar 20, anelongated cam slot 30 is provided in the bar 20 and receives a drive pin31, FIGS. 4 and 6, which extends through an arcuate slot 32 formed inthe bearing plate 23 so that the drive pin 31 may be oscillated forpivoting the bar 20 from a safe to an arm position. The drive pin 31 isdriven by a conventional one-seconddelay timing mechanism including atorsion spring 33, gear train 34, escapement device 35, and a fly-wheel36. The timing mechanism is of conventional design and functions todisplace the drive pin 31 along the slot 32 at a given rate, as dictatedby the operation of the gear train 34 and escapement device 35, so thatthe rotor bar 30, with the stab primer or detonator 22, may be displacedto an arm position, FIG. 6, whereby the primer 22 becomes coaxiallyaligned between the firing pin 14 and the igniter wafer 26 one secondafter the firing pin 14 has been displaced out of the path of the rotorbar 20.

In many instances it is necessary that the pyrotechnic material burninwardly from both ends of the grenade Gin order to prevent flamingand/or detonation. Hence, 1t 13 necessary that means be provided forremoving the fuze F and the cover cap 28 from the container C subsequentto impact. In the present invention, this result is effected by securingthe cover cap 28 to the fuze housing 17 and to a neck portion 38,provided for the container C, by layers 37 of epoxy resin, whichfracture as the stab primer or detonator 22 explodes and sets up arebounding shock front, which effectively induces a tensile stress atthe epoxy joint. Through this effect, coupled with a resulting peelingaction occurring at the joint, separation of the container C from thefuze F, is achieved.

,In assemblying the device of the instant invention,

the fuze F is first assembled and attached to a parachute 10. The fuze Fand parachute are then encased in the housing 11, FIG. 2, with thehalves 11a and 1112 being secured together by suitable means, such as anadhesive strip A, FIG. 1A. With the fuze F thus packaged within thehousing 11, assembly completion is effected by securing the fuze F tothe neck 38 of a conventional grenade by means of an epoxy rain.

The assembled device may now' be inserted into a delivery device or atube of an aircraft pod (not shown), of an attack aircraft with theadhesive strip A being removed therefrom as it is inserted. Once theaircraft is over the target, the device is ejected into the aircraftsairstream, whereupon the housing portions 11a and 11b tend to separateunder the influence of the deformed hinge portion of the housing as ittends to recover. Once the portions 11a and 11b become separated, theairstream causes the portions 11a and 11b to separate and fall away fromthe fuze F and, further, serves to deploy the parachute 10, FIG. 1B. Asthe parachute deploys, or opens, a shock force is applied to the shroudlines 10a which causes the cap 12 to retract, relative to the fuzehousing 17, carrying the firing pin 14 with it and cansing the buttressor safety was-her 16 to crush or deform. As the firing pin 14 isretracted, relative to the path of the rotor bar 20, the torsion spring33 acting through the drive pin 31 causes the rotor bar 20 to displacethe stab primer or detonator 22 into coaxial alignment with the igniterwafer 26, the conduit 25, and the firing pin 14 to thus impose an armedcondition on the device. The device is now supported through theparachute shrouds 10a and may now float to the ground. On impact, thefiring pin 14 is caused to impinge on and initiate the stab detonator 12as the cap 12 is forced toward the container C. As the detonator orprimer 22 is initiated, the epoxy layers 37 are fractured. The wafer 26now ignites the pyrotechnic P, whereupon the fuze F is parted from thecontainer C so that the pyrotechnic P may now burn from both ends in adesired manner.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. An air-arming, impact operative device comprising, in combination:

an elongated fuze housing;

a pivotally mounted rotor bar disposed in said housing and mounted forpivotal displacement from a safe position to an arm position within aplane normal to the longitudinal axis of said housing;

a stab detonator disposed within said rotor bar and adapted to extendbetween opposite faces of said rotor bar and being concentricallyaligned with said longitudinal axis when said bar is pivotally displacedfrom said safe position to said arm position;

an operative timing device connected with said bar and adapted toconstantly apply a pivoting force to said bar for driving said bar indisplacement from said safe position to said ar-m position at a givenrate;

an igniter wafer mounted concentrically about said longitudinal axis incommunication with a given pyrotechnic composition;

a conduit mounted to extend between said Wafer and said detonatoradapted to establish communication therebetween when said rotor bar isdisposed in an arm position;

a reciprocating firing pin mounted for reciprocation along saidlongitudinal axis adjacent said rotor bar and adapted to extend into abar displacement obstructing engagement with said rotor bar formaintaining said rotor bar in said safe position;

a collapsible buttress mounted in fixed relationship housing,

with respect to said fuze housing and in supporting engagement with saidfiring pin for maintaining said firing pin in displacement obstructingengagement with said rotor bar;

a skirt-like cap member telescoped in longitudinal sliding relationshipabout said housing and fixedly connected with said firing pin;

a parachute adapted to be deployed in an airstream; and shroudsconnecting said parachute with said skirt-like member adapted toslidingly retract said skirt-like member with respect to said housing assaid parachute is deployed, whereby said firing pin is caused to beretracted by said parachute against said buttress to collapse thebuttress and be displaced out of engagement with said rotor bar foraccommodating a pivotal arming displacement of 7 said bar so that saidfiring Pin may subsequently impinge against said stab detonator forfiring said pyrotechnic composition as said device is caused to impactagainst a given target. 2. The device of claim 1 further including aparachute housing mounted about said device adapted to retain saidparachute in a folded condition and subsequently release said parachutefor deployment as the device is subjected to an airstream.

3. The device of claim 2 further characterized in that said parachutehousing comprises a pair of clam shelllike members connected alongportions of their circumference by a resilient hinge means adapted toapply a member separating force to said members for releasing saidparachute and separating from said device.

4. An air-arming impact firing device for firing a given pyrotechniccomposition comprising in combination:

a device housing;

means mounted in said housing adapted to fire said pyrotechniccomposition including a stab detonator and a displaceable firing pinoperatively associated with said detonator and adapted to be displacedfrom a safe position through an arm position to a position for impactingsaid stab detonator;

a buttress formed of malleable material operatively connected with saidfiring pin and supporting the firing pin in a safe position until suchtime as a force of a buttress deforming magnitude is applied to saidfiring pin as the firing pin is driven from its safe to its armposition, whereby said firing pin may be maintained in its safe positionagainst forces of less than a buttress deforming magnitude as it isapplied to said firing pin;

an inertia weight afiixed to the firing pin and moveable in unisontherewith; and

a parachute having shroud lines connected to said inertia weight;

the construction and arrangement being such that when the parachuteopens it applies the buttress deforming force to the firing pin andmaintains the firing pin in arm position until the device impacts anobject, whereupon the shroud lines slacken and permit the inertia weightto move, carrying the firing pin into contact with the detonator.

5. The device of claim 4 further characterized in that said buttress isa frusto-conical disk surrounding the firing pin, its smaller endabutting a shoulder on the firing pin and its larger end abutting an endwall of the the disk, when deformed, being substantially flat.

6. Apparatus for arming and firing a moveable ordnance member subjectedto acceleration and deceleration forces, comprising:

a weight carried by the member and restrained against movement from asafe initial position by a deformable frusto-conical washer, havingfreely slidable abutment edges at opposite ends thereof, the smalleredge adapted to decrease in diameter and the larger edge adapted toincrease in diameter whem the washer is deformed toward a flattenedposition;

said weight adapted to move rearwardly relative to the direction ofmovement of the member and flatten said washer upon application of aforce acting relative to the weight and washer;

said weight being in armed position when the washer is flattened;

said weight adapted to move forwardly relative to the direction ofmovement of the member to a firing position by its inertia when themember rapidly decelerates; and

an igniter adapted to be initiated by the Weight when the weight movesto firing position.

7. Apparatus for arming and firing an ordnance member subject toacceleration and deceleration forces comprising:

an inertia member carried by said ordnance member adapted to movebetween a safe and arm position;

a deformable frusto-conical washer, engaging said inertia member andrestraining said inertia member against movement from the safe position;

said washer having freely slideable abutment edges at opposite endsthereof, the smaller edge adapted to decrease in diameter and the largeredge adapted to increase in diameter when the washer is deformed towarda flattened position;

said inertia member being adapted to move relative to the washer uponapplication of a force on said inertia member sufficient to deform saidfrustoconical member;

said inertia member being in an armed position when the washer isdeformed.

References Cited UNITED STATES PATENTS 1,311,678 7/1919 Cartwright102-78 1,356,828 10/ 1920 Rockwell 10278 2,764,092 9/1956 Massey lO2-73SAMUEL FEINBERG, Primary Examiner.

BENJAMIN A. BORCHELT, Examiner.

G. H. GLANZMAN, Assistant Examiner.

7. APPARATUS FOR ARMING AND FIRING AN ORDNANCE MEMBER SUBJECT TOACCELERATION AND DECELERATION FORCES COMPRISING: AN INERTIA MAMBERCARRIED BY SAID ORDNANCE MEMBER ADAPTED TO MOVE BETWEEN A SAFE AND ARMPOSITION; A DEFORMABLE FRUSTO-CONICAL WASHER, ENGAGING SAID INERTIAMEMBER AND RESTRAINING SAID INERTIA MEMBER AGAINST MOVEMENT FROM THESAFE POSITION; SAID WASHER HAVING FREELY SLIDABLE ABUTMENT EDGES ATOPPOSITE ENDS THEREOF, THE SMALLER EDGE ADAPTED TO DECREASE IN DIAMETERAND THE LARGER EDGE ADAPTED TO INCREASE IN DIAMETER WHEN THE WASHER ISDEFORMED TOWARD A FLATTENED POSITION; SAID INERTIA MEMBER BEING ADAPTEDTO MOVE RELATIVE TO THE WASHER UPON APPLICATION OF A FORCE ON SAIDINERTIA MEMBER SUFFICEINT TO DEFORM SAID FRUSTOCONICAL MEMBER;